A large-scale assessment of lakes reveals a pervasive signal of land use on bacterial communities.

Lakes play a pivotal role in ecological and biogeochemical processes and have been described as "sentinels" of environmental change. Assessing "lake health" across large geographic scales is critical to predict the stability of their ecosystem services and their vulnerability to anthropogenic disturbances. The LakePulse research network is tasked with the assessment of lake health across gradients of land use on a continental scale. Bacterial communities are an integral and rapidly responding component of lake ecosystems, yet large-scale responses to anthropogenic activity remain elusive. Here, we assess the ecological impact of land use on bacterial communities from over 200 lakes covering more than 660,000 km2 across Eastern Canada. In addition to community variation between ecozones, land use across Eastern Canada also appeared to alter diversity, community composition, and network structure. Specifically, increasing anthropogenic impact within the watershed lowered diversity. Likewise, community composition was significantly correlated with agriculture and urban development within a watershed. Interaction networks showed decreasing complexity and fewer keystone taxa in impacted lakes. Moreover, we identified potential indicator taxa of high or low lake water quality. Together, these findings point to detectable bacterial community changes of largely unknown consequences induced by human activity within lake watersheds.

Serum theophylline profile with once-daily theophylline (Uniphyl) following conversion from intravenous theophylline in adult asthmatic patients.

Although guidelines are available for conversion from intravenous (IV) theophylline to twice-daily, oral, controlled-release theophylline, the optimal method for conversion to Uniphyl, a chronotherapeutically formulated, once-daily theophylline preparation, has not been previously evaluated. The present study was designed to prospectively evaluate a method for converting patients from IV theophylline to Uniphyl, to formulate simple, practical dosage recommendations for use in clinical practice. Ten patients with acute exacerbation of asthma receiving IV theophylline for > or = 48 hours and with steady state serum theophylline concentrations (STCs) between 4.5 and 15.5 mg/L (25 and 86 mumol/L) were enrolled into the study. Patients with STCs > or = 4.5 and < 12 mg/L (> or = 25 and < 66 mumol/L) and those with STCs > or = 12 and < or = 15.5 mg/L (> or = 66 and < or = 86 mumol/L) received their first Uniphyl dose immediately following termination of IV theophylline (No Time Lapse [NTL] group) and after a 4-hour delay (Time Lapse [TL] group), respectively. The differences in the area under the curve values between Uniphyl dosing and IV theophylline were 11% in the NTL group (1214.6 +/- 247.9 mumol/h.L-1 vs 1370.4 +/- 148.1 mumol/h.L-1, 95% confidence interval, 74% to 103%; P = 0.068) and 10% in the TL group (1959.4 +/- 165.1 mumol/h.L-1 vs 1784.6 +/- 119.4 mumol/h.L-1, 95% confidence interval, 103% to 117%; P = 0.013).(ABSTRACT TRUNCATED AT 250 WORDS)